CHA 



CHA 



delicacy. They abound in Sweden, Russia, 

 and Siberia, and from their extraordinary 

 stupidity fall an easy prey to the clumsi- 

 est stratagem of the fowler. See Plate 

 IV. Aves, fig. 4 and 5. 



CHARCOAL, is wood burnt through, 

 and suddenly extinguished by being co- 

 vered with fresh earth. It is perhaps 

 one of the most durable substances with 

 which we are acquainted, not being de- 

 composed either by the air or the water. 

 It is of great use in many processes where 

 a strong heat is required : it is an antisep- 

 tic ; but very dangerous as fuel in confin- 

 ed places. In chemistry, the terms car- 

 bon and charcoal were long confounded, 

 and supposed to mean the same thing ; 

 but the experiments by Morveau and 

 others have pointed out the precise dis- 

 tinction. See CARBON. 



When charcoal is prepared in the usual 

 way, by exposing wood in close vessels to 

 a red heat, it always contains a portion of 

 hydrogen. For if a quantity of this char- 

 coal be exposed to a strong heat in a re- 

 tort of porcelain, iron, or coated glass, a 

 great quantity of gas is obtained. The gas 

 which comes over first is a mixture of car- 

 bonic acid and heavy inflammable gas ; 

 but the proportion of carbonic acid di- 

 minishes, and at last it ceases to come 

 'over at all ; yet the inflammable gas con- 

 tinues as copious as ever. The evolution 

 of these gases was long ascribed by che- 

 mists to the water which charcoal usually 

 contains, and which it is known to absorb 

 from the atmosphere with, considerable 

 avidity. If that were the case, the pro- 

 portion of inflammable gas ought to dimi- 

 nish at the same rate with the carbonic 

 acid; the hydrogen of the one being 

 equally derived from the decomposition 

 of water with the oxygen of the other. But 

 as the evolution of inflammable gas conti- 

 nues after that of carbonic acid has ceased, 

 it is scarcely possible to deny, that the hy- 

 drogen which thus escapes constituted a 

 component part of the charcoal. 



If, therefore, we consider the experi- 

 ments of Morveau on the combustion of 

 the diamond asdecisive,we must conclude 

 that common charcoal is composed of 

 three ingredients, namely, carbon, hy- 

 drogen, and oxygen. It is of course a 

 triple compound. 



When common charcoal is exposed for 

 an hour, in a close crucible, to the strong- 

 est heat of a forge, it ceases to emit gas; 

 and no temperature is sufficient to expel 

 gas from charcoal thus treated. Desormes 

 and Clement have endeavoured to demon- 

 strate, that by this treatment common 



charcoal is deprived of the whole of its 

 hydrogen. The same chemists tried the 

 combustion of charcoal obtained from a 

 variety of other substances exposed to 

 the heat of a forge, as pitcoal, animal sub- 

 stances, and various vegetable substan- 

 ces, and found the products exactly the 

 same. Hence they conclude that char- 

 coal is in all cases the same, provided it 

 be exposed to a heat strong enough ; and 

 they conclude too, that by this strong heat 

 the whole hydrogen of common charcoal 

 is expelled. 



These facts enable us to conclude, that 

 there are two species of charcoal, name- 

 ly, common and prepared charcoal. The 

 first contains three ingredients, carbon, 

 hydrogen, and oxygen ; the second is de- 

 prived of a portion of its hydrogen and 

 oxygen. It consists chiefly of carbon and 

 oxygen united; but it still retains a small 

 portion of hydrogen, and is not, there- 

 fore, strictly speaking, a pure oxyde of 

 carbon, though it approaches very nearly 

 to such an oxide. 



CHARGE, in gunnery, the quantity of 

 gunpowder and ball wherewith a gun is 

 loaded for execution. The rule for charg- 

 ing large pieces in war are, that the piece 

 be first cleaned or scoured withinside : 

 that the proper quantity of powder be 

 next driven in and rammed down ; care 

 however being taken, that the powder 

 in ramming be not bruised, because that 

 weakens its effect : that a little quantity 

 of paper, hay, lint, or the like, be ram- 

 med over it, and that the ball or shot be 

 intruded. If the ball be red-hot, a tam- 

 pion or trencher of green wood, is to be 

 driven in before it. The weight of the 

 powder necessary for a charge is com- 

 monly in a subduple proportion to that of 

 the ball. 



CHARGE, in heraldry, is applied to the 

 figures represented on the escutcheon, by 

 which the bearers are distinguished from 

 one another; and it is to be observed, that 

 too many charges are not so honourable 

 as fewer. 



CHARGED, in heraldry, a shield car- 

 rying some impress or figure, is said to 

 be charged therewith ; so also when one 

 bearing, or charge, has another figure 

 added upon it, it is properly said to be 

 charged. 



CHART, or hydrografchical map, in na- 

 vigation, is a representation, in piano, of 

 a part, or of the whole, of the water on 

 the surface of the globe, and the adjacent 

 coast. There are various kinds of charts, 

 as Globular, Plane, Mercator's, &c. 



CHART, globular, is a projection, so call- 



